Iris-diaphragm.



M. E. SMITH.

I IRIS DIAPHRAGM. APPLICATION FILED iuvls. 1913.

1,161,739. PatentedNov. 23, 1915;

Fiql.

Fig.3.

5 FIqZ. 6

-|3 v 58 ll 8 II" Witnesses. Inventor hm E m.

Murray E Smith, y Wfl Q His Attorr xey.

. portions broken away;

UNITED STATES PATENT OFFICE.

' MURRAY E. SMITH, OF PITTSFIELD, MASSACHUSETTS, AS SI GNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

IRIS-DIAPHRAGM.

To all *uihom it may concern;

Be it known that I, MURRAY E. SMITH, a citizen of the lfnited States, residing at Pittsfield, in the county of Berkshire, State of ii'lassachusetts, have invented certain new and useful Improvements in lris- Dia-' phragms, of which. the followin is a specification.

My invention has reference to an iris diaphragm and has for its object an improvement in a device of this character.

Iris diaphragins are usually constructed with overlapping vanes which are movable across the light opening to vary the sizeof the same and at the same time to keep the opening practically circular and concentric with the axis of the lens with which the diaphra m is usually used. With diaphragms such as are commonly used, it is, on account of the mass of metal at the center resulting from the overlapping of the vanes, impossible completely to close the central opening. the size of the minimum opening depending upon the number and thickness of the vanes. In order completely to intercept the light, it is necessary either to provide some special device for finally closing the opening, such as a finger or projection on one or more of the vanes, or else to use a shutter in addition to the diaphragm for totally intercepting-the light.

My invention comprises an iris diaphragm usual type, and at the same time makes pro vision for intercepting substantially all of the light when desired.

For a fuller understanding of my invention, reference may be had to the accompanying drawing. in which- Figure 1 is a top plan view of an iris diaphragm embodying my invention, with Fig. '2 is a perspective View of a lamp casing with the iris diaphragm attached thereto, and Fig. 3 is a section on a reduced scale along the line a-a of Fig. 1.

Referring to the drawings, 1 is the casing of alamp in conjunction with which I have here illustrated my invention. The lamp casing which I have here illustrated is commonly used for theatrical purposes and is provided with a door 2 by which access may be had to the lamp. and with ventilating openings 3. The casing of the lamp islpr ovided with supporting gu1de lugs 4, within Specification of Letters Patent. Application filed May 15, 1913. Serial No. 767,815.

"which preserves all of the advantages oft he Patented Nov. 23, 1915.

which the frame, in which my novel form of iris diaphragm is mounted, is received. This frame comprises a base plate 5, having an opening 5 in the middle and provided with an annular recess 3 on the lower or back face. An annular ring 7 is received within the recess 6 and is secured to the base in any suitable manner. This ring is provided on its upper face with a series of radial slots 8. These slots serve as guides for iris vanes and are not all equally spaced apart, so that some of the vanes move across the base opening more rapidly than the others, as will be more fully hereinafter eX- plained. I have'here illustrated two adjacent slots located at the points that would be obtained by dividing the angular space in the ring by the number of vanes, in this case 21. The next successive slot, however, instead of being located at thc next one of the points of subdivision thus obtained is offset from this point. For example, the slots 8 are located one twenty-first of 360, or about 17 8 apart. The slot 8", however,

instead of being located this same angular distance from the nearest of these slots 8 is separated therefrom by a less distance. The next two slots 8 are again arranged in the same manner as the first two slots 8 but in order 'to bring the angle between the first of each of these sets of slots up to three twenty-firsts 01: 360", the angular distance between the first of these latter two slots and the slot 8 'will be more than one twenty-first of 360. A rotatable ring 9 is also received within the recess 6 above the ring 7 and is provided with a stud 10 extending upwardly through a segmental slot 11 formed in the upper face of the base plate 5. The upper end of this stud will, of course, be provided witha suitable handle. A series of vanes 12 are provided at one end with downwardly extending pins 13 engaging the radial slots 8, and the other ends of the vanes are provided with pins 14, by which the vanes are pivoted to the rotatable ring 9. The particular vanes which engage the slots 8, I have indicated by the reference numeral 12 and the vanes which engage the offset slots 8* by- 1-2". I have shown, partly dotted and partly in full lines, one complete vane 15.

The base plate is provided with spring clips 16, by which the attachment is secured to the lamp as shown in Fig. 2. The attachment is also provided with suitable pins 17 which limit the movement of the attachment and cause the opening of the same to register with the lamp opening.

The vanes 12, which may be made of any suitable material, such as sheet metal, are assembled in overlappingposition, the pins lficngaging the radial slots as above indicated, and the pins 14- being received in the openings in the'rotatable ring 9, and, when the vanes are in the open position, stud l0 will be located at the right hand end of the slot 11. Now, in order to close or partially close the opening, the stud and rotatable ring 9 are moved anticlockwise/and the vanes 12 are carried across the opening 5*, always leaving an opening which is substantially concentric with the base opening.- Now, it will be seen that those vanes, whose pins 13 engage the slots 8*, will move across the opening a little more rapidly than the remaining vanes, with the consequence that the final opening will be substantially closed by a third'of the vanes, namely the vanes 12, the remaining vanes, being in a position toform'the concentric opening indicated in dotted lines, and in practice where no special provision for finally closing the opening is made, an appreciable opening as large or larger than that indicated by dotted lines will remain and seriously interfere with the effectiveness of the device, whereas the relatively small opening which results with vmy invention is unobjectionable for certain,

What I claim as new and desire to secure by Letters Patent of the United States is 1. In an iris diaphragm, a base provided with a central opening, a series of overlapping vanes mounted upon the base and arranged around the opening and adapted to move across the opening and means for moving a part of the vanes across the open ing more rapidlv than the others.

In an iris diaphragm, a base provided with a central opening, a series of overlap ping vanes arranged around the opening and adapted to, move across the opening so as to form a substantially circular opening concentric with the base opening, and means for moving a part of the vanes across the opening more rapidly than the others,

3. In a light shutter, a base provided with a central opening and a series of unequally spaced, radially extending grooves, a. rotatable m'ember mounted upon the base, and a series of vanes, each of which is provided at one end with a memberadapted to engage one of said grooves, the other end being pivoted to said rotatable member whereby part of thc vanes move across the 0 ening in the base more rapidly than the at cm and at the end of the movement substantially complete the closing of said base open- In combination, abase provided with a substantially central opening and an annu-.

lar recess one side extending around the opening, a ring adapted to be secured wlthin saidrecess and provided on the inner side with a series of unequally spaced radially extending slots, :1 ring rotatably mounted in the recess within said first ring, and a series 4 of overlapping and segmental yanes which are pivoted at their outer ends at substantially equally distant points to said rotatable ring, the opposite ends being provided with members for engaging said slots. In witness whereof, I have hereunto set my hand this 12th day of May, 1913. MURRAY E. SMITH. Witnesses:

A. O. Scnnnz, A, H. BRAMBERS. 

